1. Technical Field
Embodiments generally relate to serial interconnect communications. More particularly, embodiments relate to the use of digital non return to zero invert (NRZI) signals in serial communications between a physical layer and a link layer, for various information exchanges not limited to data.
2. Discussion
Serial interconnect IOs (input/output interfaces) such as USB (Universal Serial Bus, e.g., USB Specification, Rev. 2.0, Apr. 27, 2000, USB 3.0 Specification, Rev. 1.0, Nov. 12, 2008, etc.) IOs can be used to connect computing systems to a wide variety of devices such as digital cameras, keyboards and mice. Indeed, a typical computing system might include multiple integrated USB ports, which can enable devices to communicate with the computing system through the host controller. The USB physical layer (PHY) and the link layer can either be on the same piece of silicon or be on separate silicon chips. In case of the PHY and the link being on different chips, the link layer can be integrated with the processor, which benefits from lower voltage design technologies. Information packets may be passed between the PHY and link layer via an interface port. Current architectures for USB packet communications between the PHY and link layer include a parallel bus, which can have a relatively high pin count. If multiple USB ports need to be supported, the cost of pin count increase could become too high for an SoC implementation to accept.